RT Journal Article
SR Electronic
T1 Diversity, biogeography, and evidence for endemism of SAR11 bacteria from the Arctic Ocean
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 517433
DO 10.1101/517433
A1 Susanne Kraemer
A1 Arthi Ramachandran
A1 David Colatriano
A1 Connie Lovejoy
A1 David A. Walsh
YR 2019
UL http://biorxiv.org/content/early/2019/01/10/517433.abstract
AB The Arctic Ocean is relatively isolated from other oceans and consists of strongly stratified water masses with distinct histories, nutrient, temperature and salinity characteristics, therefore providing an optimal environment to investigate local adaptation. The globally distributed SAR11 bacterial group consists of multiple ecotypes that are associated with particular marine environments, yet relatively little is known about Arctic SAR11 diversity. Here, we examined SAR11 diversity using ITS analysis, metagenome-assembled genomes (MAGs) and metatranscriptomic datasets. Arctic SAR11 assemblages were comprised of the S1a, S1b, S2, and S3 clades, and structured by water mass and depth. The fresher surface layer was dominated by an ecotype (S3-derived P3.2) previously associated with Arctic and brackish water. In contrast, deeper waters of Pacific origin were dominated by the P2.3 ecotype of the S2 clade, within which we identified a novel subdivision (P2.3s1) that was rare outside the Arctic Ocean. Arctic S2-derived SAR11 MAGs were restricted to high latitudes and included MAGs related to the recently defined S2b subclade, a finding consistent with bi-polar ecotypes and Arctic endemism. These results place the stratified Arctic Ocean into the SAR11 global biogeography and have identified SAR11 lineages for future investigation of adaptive evolution in the Arctic Ocean.